I've always found an old style Coleman Lantern with the cloth mantles to work real good for that purpose. I've heard of the blue light being used, but never used one myself. How many use a stride stick? If you have any kind of animalwalking off, take a stick and measure the distance between foot prints. When you loose track of the animal and find no blood, set that measure stick on the last print and it will usually point/mark where to look for the next foot print. This is slow going mind you, but it can help you get over the hard parts of a track job.